1. Field of the Invention
The present invention relates to an elastic wave device which is used in a cellular phone, a wireless LAN terminal, and the like.
2. Description of the Related Art
In recent years, a trend has been increasing to transform an elastic wave device into a module and to mount the module in a variety of products such as a cellular phone and a wireless LAN terminal. The modules mounted in the variety of products are desired to be miniaturized and of a low profile as well as to have high reliabilities. On the other hand, the elastic wave device, which utilizes a wave propagating on its surface, needs to have an appropriate space structure because it is a key to realization of miniaturization and high reliabilities.
FIG. 13 is a schematic cross-sectional view showing a configuration of a conventional elastic wave device. As shown in FIG. 13, elastic wave device 101 includes piezoelectric substrate 102, IDT electrode 103, internal electrode 104, support pillar 105, top panel 107, conductor pattern 108, insulation protector 109, external electrode 110, and connection electrode 111.
IDT electrode 103 is disposed on piezoelectric substrate 102. Internal electrode 104 is disposed on piezoelectric substrate 102 and connected to IDT electrode 103. Support pillar 105 is disposed on piezoelectric substrate 102 and provided around IDT electrode 103.
Top panel 107 is formed on the support pillar 105 in such a manner as to cover space 106 above IDT electrode 103. Conductor pattern 108 is formed above top panel 107. Insulation protector 109 covers support pillar 105 and top panel 107. External electrode 110 is disposed above insulation protector 109. Connection electrode 111 is formed through insulation protector 109, to electrically connect external electrode 110 and internal electrode 104 to each other.
In this configuration, in elastic wave device 101 in the related art, conductor pattern 108 has been formed in order to obtain inductance on top panel 107 in an attempt to improve attenuation characteristics.
As information of prior art document related to the invention of this application, for example, International Publication No. 2006/134928 is known.
As described above, in elastic wave device 101 in the related art, conductor pattern 108 has been formed to give inductance on top panel 107. This structure would cause IDT electrode 103 and conductor pattern 108 formed to obtain inductance to interfere with each other, so that properties of the elastic wave device 101 might possibly be deteriorated.